A two-pole generator working into a 60-Hz load must operate at exactly 3600 RPM if it is a synchronous generator, and within 10% of 3600 RPM if it is an induction generator of conventional design. Generators with 4, 6 or 8 poles must operate at proportionately lower RPMs to deliver energy directly into a 60-Hz load. A generator can be designed to operate at a much higher RPM in order to reduce its weight, but its output frequency will then necessarily be much higher than the commonly used 60 Hz.
To change a DC or high-frequency AC output to 60 Hz has until now required a costly, complicated inverter circuit. The present invention describes how, by heterodyning the outputs of two high-frequency generators operated at frequencies which differ from each other by 60 Hz, only a simple rectifier circuit is needed to deliver power to the load at 60 Hz.